Hi Lowranking (pun intended )!
I use CaptureNX mostly, some times Paint Shop pro and am currently testing Lightroom but only with an eye to sorting and cataloging.
CaptureNX works with RAW-files from Nikon (NEF) but also with standard jpegs and tiffs albeit not all the nice functions will then work.

Here's the software I use. Note that I won't necessarily use all this every time, but that some software is better suited to certain tasks than others.

1. ACDSee Pro - The very first program my RAW files see. Used for it's extensive cataloguing facilities.

2. Capture NX - Invaluable as it retains the settings you chose in-camera at the shoot. Also very good at compensating for lens distortion (on Nikon lenses, obviously).

3. Photomatix Pro - The only HDR editor I can use with any degree of consistency (says more about me than it does about any other HDR software).

///////////At this point it's worth noting that if you are intending to process using HDR techniques then you might as well skip Capture NX as it's not possible to make identical corrections across the full range of images needed for HDR)//////////

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My main photo editor is Photoshop CS2. I also have Photomatix Pro and I use Canon's DPP to convert my 40D's RAW files. If you are looking for cheaper alternatives to Photoshop you could do worse than check out GIMP (see my post here). It may be free but this is a capable program. I am not a great fan of the multiple free floating window interface it uses but that is a personal thing. I have decided to keep GIMP for quick re-touching on my low-powered computer with Photoshop on the main machine for the serious work.

I'm using CS2 for my editing, and ACDSee for cataloging and browsing. If you want something that's free, fast and very basic you could give Google's Picasa a try (PC only at this time). Photoshop Elements offers a nice combination of flexibility, ease and price. It's really worth looking at as well.

If price is the biggest concern: Google's Picasa

If you want a well rounded program and price is not a big concern: Photoshop Elements